Ever since I was young, I have always been fascinated with the idea of “Attractiveness”. We all know when we find someone attractive: If you show someone a picture of a person, they find attractive, they will be certain of their judgment. There will be no hesitation and no second thoughts. But if you ask why, not everyone can give you a straightforward answer. Some people can recognize patterns in who they find attractive, but many don’t. My fascination lies in the Why. Why do I find this specific person attractive? What physical patterns do I find more appealing? What biases shape my preferences? When do cultural pressures start and end? There is an abundance of research material attempting to decipher these patterns, which can be affected by culture, time and personal experience. The idea of attractiveness will not only differ for people living in Australia and Japan, but also for Swedes in their 30s and Swedes in their 60s.

Psychology offers important insights; can technology also help us find patterns? Facial embedding models exist, whose purpose is to create latent space representation of images. Can these latent spaces find patterns within someone’s ideal of attractiveness? Can these patterns be disentangled from the latent space? Can a Machine Learning model learn our individual and personal preferences for what we find attractive? Before I begin, however, I would like to delve deeper into the intricacies of attractiveness. I want to understand a little more about how we view attractiveness, how it affects us and the people around us, how it can bias our decisions, and whether there are proven patterns. Let us review existing literature and explore what the real experts have uncovered. A note of caution: this post will not be able to cover all research in the subject, as this could take years and could merit its very own paper. Secondly, reducing people to data points such as attraction ratings might feel shallow. We are all more than our physical attractiveness… or are we?

The Apple of Discord

Beauty is a signal. At its most primal level attempts to transmit cues of health, vitality and/or survival. How we interpret this signal is shaped by culture, personal experience, our environment and external social pressures. As our species has evolved, we can now look away from its biological cues and appreciate it in a more artistic or aesthetic manner. Beauty, however, plays a big part in everyone’s lives. To deny its impact would be to ignore the superficial nature of our species. Cuisine offers the perfect analogy: Our food habits have evolved beyond simple sustenance and nutrition. Yet indulging in exotic foods at elegant restaurants still fulfills the same basic need of nutrition.

The famous quote from the 1876 novel Molly Bawn would tell you: Beauty is in the eye of the beholder. The idea of beauty is extremely personal because too many factors play a part. But that does not mean that there are no patterns. Before we begin our search for patterns, we need to ask ourselves a basic question: why do we choose a mate? What is the main reason behind our choice? There are three main models of sexual selection 1 2:

  • Aesthetic model: One favours a mate because they are attractive, and not because they indicate good features or genes that enhance survival of offspring.

  • Good Genes model: One favours a mate because they present features indicative of good offspring survival.

  • Good provider model: One favours a mate because they indicate the ability to provide for us and/or offspring.

These all sound plausible, right? Don’t worry about choosing, because these are not competing models. Instead, mate dynamics involve some combination of these models. The perspective article by Sugiyama (2015) covers this topic in-depth. Our ancestors had to find survival fitness cues in their potential mates without access to modern concepts of medicine, health, or personality assessments. 3 Modern courting allows potential mates to get to know each other at a slower pace than our ancestors did, but we still do not request medical health results or provide personality questionaires. Instead, we continue to make use of similar, if not the same, cues to aid in our decision-making.

Men and women can be driven by different cues, even if they can agree of someone’s physical attractiveness. I quote Sugiyama: “Female mate value is linked to age, health, fertility, fecundity, and parity (e.g., Buss, 1992; Symons, 1979, 1995)”. A woman’s health and reproductive fitness is key to a man’s offspring survival, as ill-health, food constraints or other stressors can reduce fecundity or affect the health of an unborn child. Again, I quote Sugiyama: “In addition to genetic quality, male mate value includes provision of material resources to mates, their offspring, and other adults (Gurven et al., 2000; Hewlett, 1992; Kaplan et al., 2000; Marlowe, 1999a, 1999b, 2001; Sugiyama & Chacon, 2000, in press).” Child rearing comes at great cost to women therefore productive ability of a potential mate provides a greater benefit.

To the Fairest

For one of these reasons Strife [Eris] threw an apple as a prize of beauty to be contended for by Hera, Athena, and Aphrodite; and Zeus commanded Hermes to lead them to Alexander on Ida in order to be judged by him.

— Apollodorus, Library, Epitome 3.2 (Frazer’s 1921 translation)

Quick Glances

What cues or attributes make someone attractive? Let us start with straightforward cues that we all, subconsciously, apply in our daily life.

  • Skin: Infections, parasites and other illnesses pose less of a threat to humans thanks to advances in medicine, but this is a late occurence in human history. Bug bites, skin blemishes or assymetrical features are possible cues to an individual’s past and current health. 3 Multiple studies have found that skin texture can influence attractiveness ratings after controlling for other factors.

  • Hair: Quoting from Sugiyama (2015): “Grammer et al. (2002) found that hair length was significantly correlated with female attractiveness”.3 Our hair grows at an approximate daily rate of 0.35 millimeters, according to the American Academy of Dermatology (AAD). But this growth rate can be affected by nutrition, such as starvation or lack of nutrients. Hair will become damaged, may have noticeable changes in tone or may even start falling. Longer hair tends to be preferred by cultures around the world, and it seems to provide cues into health and reproduction in women. Quoting Sugiyama: “[…] collected hair samples and contributor information from over 200 women ages 13 to 73 and found that younger, higher reproductive value women tended to have longer hair than older women, as predicted if higher reproductive value women were more likely to use their hair as an advertisement of that fact.”. Hair also tends to grow faster in women around the age of peak fertility.

  • Waist to Hip Ratio (WHR): is a cue that is used differently between men and women. Men tend to prefer lower WHR, ranging between 0.6 and 0.8 depending on the culture, but trending to 0.7. To control for cultural effects, the WHR was analyzed for Playboy Playmates and Miss America. Although weight of the models has declined over the years, the WHR has stayed at approximately 0.7. It is worth noting than men tend to prefer the WHR that they are exposed to: if their environment tends to have higher or lower WHR, they will prefer this over the trend of 0.7. Women, however, tend to prefer a WHR of 0.9 for men. Sugiyama (2015) has proposed that _“Waist to Buttock Ratio” should also be considered in future research as it may play a part in attraction. 3

Sugiyama was not able to find many cues into dental health, which surprises him given the size of the modern dental hygiene industry. Dental diseases or poor teeth can lead to problems when eating. Bad breath can be a marker for infections, providing another insight into an individuals health.

Facial and Bodily cues

When do we take attractiveness cues from the body and the face, and which one takes precedence? Confer et. al. (2010) theorized that men and women treat these cues differently. 4 There are two key concepts that we need to define before we continue, reproductive value and fertility. Fertility is the probability of reproduction at a point in time. For example, during ovulation a woman has a high chance of reproduction. Reproductive value is the expected value of future reproduction. For example, a 17-year-old woman has a higher reproductive value than a 39-year-old woman because over her future lifetime the former has a higher probability of bearing more children than the latter. But an ovulating 17-year-old woman is significantly more fertile than an ovulating 39-year-old woman. Fertility is a point in time, while Reproductive value is a future average or probability. 5

Studies had shown that faces and bodies provide independent contributions to attractiveness. Confer et. al.’s central hypothesis was, I quote: “although many cues regarding a woman’s health and fertility can be gleaned from both her face and her body, each component conveys a subset of cues that are not conveyed by the other component”. 5 They hypothesized that a woman’s body could provide more cues about fertility, while a woman’s face could provide more cues about reproductive value. Therefore, men would assign different priorities to these depending on their mating strategies: If a man is looking for shorter-term mating, then he would prioritize cues from the body because fertility is more important. If a man is looking for longer-term mating, then he would prioritize cues from the face because reproductive value is more important. They also hypothesized that women would not be affected by these changes in priorities when looking for potential male mates.

To test this hypothesis they gathered 381 subjects, 194 male and 187 female, all of them university students. Two full body and fully clothed stock photos were purchased by the researchers. Participants were divided into 2 groups, a short-term mating group (i.e. one-night stand) and a long-term mating group (i.e. long-term relationship). Participants were to suppose they were single and had to make a choice given their mating status. They were then provided with a “stick figure” drawing super-imposed on an image of an individual from the opposite-sex and were asked to make a choice: Show the face or the body of the individual. 61% of all male participants preferred to see the face, while females chose it 69% of the time. When split into their respective groups, 74% of long-term mating males preferred to see the face, while only 49% of the short-term mating males chose to see the face. Both female groups preferred to see the face 73% of the time. 5 The study concludes that a face may provide more information about health, fertility and other cues than the body. It also notes that their sample was only from young people therefore it may not be representative of a different age group or wider population. It is my view that this experiment could be replicated on a greater sample size, including a wider set of age groups, controlling for additional variables such as cultural background or religion, which may influence participant’s choices.

Symmetry

Symmetry affects our perception of beauty: The more symmetrical a person’s body is, the more we will tend to find it attractive. Humans, just as other animals, are designed to be bilaterally symmetrical. Developmental disturbances and stressors are expected to affect both sides equally but small random variations may occur. These small variations are called fluctuating assymetry. 3 According to other referenced studies, FA can increase via exposure to stressors or environmental perturbations. Some examples are parasites, pollutants, extreme temperatures or genetic perturbations. Symmetry can be a cue to an individual’s resilience to developmental or environmental perturbations. In Gangestad et al. 1994 122 undergraduate students underwent measurements for seven paired body traits: feet breadth, ankle breadth, hand breadth, wrist breadth, elbow breadth, ear breadth, and ear length. These measurements provided the researchers with the FA of each participant. 2 60 were men and 62 were women, while 51% were Caucasian, 29% Hispanic, 5% Oriental, 4% African American, and 3% Native American. The study also considered other variables that could affect the results, such as marital status and sexual orientation.

The study found that FA is negatively correlated with a person’s number of lifetime sexual partners, for both men and women. This means that more symmetrical people report having more sexual partners. It also found that people with greater symmetry had their first sexual experience at a younger age, particularly men. Interestingly, men’s facial attractiveness correlates significantly with FA, while the correlation for women was “small and nonsignificant”. Other studies lead to similar results, quoting Sugiyama: “Waynforth (1995) found FA related to higher morbidity and lower fecundity and marginally associated with higher age at first reproduction and fewer lifetime sex partners among Mayan men in Belize”.3

Cross-Cultural Effects

Difference in culture affect our perception of attractiveness. In Buss, 1989, a questionnaire was given to a sample of 10,047 participants from 33 countries over 5 continents. 6 Sample sizes varied between countries, with 55 being the lowest (Iran) and 1,491 being the highest (Mainland US). Mean age also fluctuated from 16.96 years (New Zealand) to 28.71 (West Germany). The study reminds us that the sample is not representative of each individual country, as the samples were obtained from different sources. However, the overall sample is representative of cultural differences. The specific tables and breakdowns per country can be found within the paper. A questionnaire was prepared and translated when necessary. It first asked about personal information such age, religion and marital status, among others. It then asked at which age the respondent preferred to marry, and what age difference was expected between the respondent and a spouse. Finally, it asked the respondent to rate 18 characteristics that were desired in a potential mate.

Earning capacity showed a significant cross-cultural difference, I quote: “South American, North American, Asian, and African samples valued earning capacity more than did Western European samples”. The paper also obtained a predicted sex difference: Women rate this trait in a potential mate higher than men do. The closely related trait of Ambition and Industriousness showed similar gender results, with women expressing a higher value for this trait than men. Overall, no sample rated this trait low, but the Netherlands, Great Britain, West Germany and Finland expressed less preference for this characteristic than other samples. 6

The next trait, age difference, continued to show patterns for genders. Men preferred younger mates, while women preferred mates who were older. The study states “which is consistent with the hypothesis that males value mates with higher reproductive capacity.”. The paper makes another finding, if the mean age at which men prefer to marry (27.49 years) is subtracted from the mean age difference between partners as preferred by males (2.66 years) it can be inferred that males prefer marrying women who are approximately 24.83 years old, “this age preference is closer to peak female fertility than to peak reproductive value”. The samples are a wild variance of age difference, but they all show the same pattern. A difference in marriage systems, for example, could explain some difference in age. Polygynous mating systems tend to lead to males marrying when they are older, in comparison with monogamous systems. 6

Good looks are more highly rated for men than for women. Even in countries where the gender differences were smaller (such as India, Poland and Sweden), it was still skewed towards men. Chastity, or “having no previous experience in sexual intercourse” varied a lot between cultures. Countries such as China, India, Indonesia, Iran, Taiwan and Palestinian Arabs in Israel rated chastity as an important trait in a potential mate. Countries such as Sweden, Norway, Finland, the Netherlands and France rated chastity much lower. The study states that this “yield[s] equally powerful evidence of proximate cultural influences on the degree of importance placed on lack of prior sexual intercourse in a potential mate.”. Interestingly, the rating of chastity seems to follow a correlation with how conservative a culture is, but this remark was not in the scope of the paper. 6

The Face That Launched a Thousand Ships

Was this the face that launched a thousand ships? And burnt the topless Towers of Ilium? — Chrisopher Marlow, Doctor Faustus

At some point in your life, you would have heard, or even believed, that more attractive people are more likely to get what they want. There is a stereotype that good-looking people are more likely to get treated better, or tend to lead a happier life. Is it true? Attractiveness does influence daily life. Berscheid et al. 1974 gathered literature to find the answer to this very question. 7

Infancy

Babies have an ingrained idea of facial attraction, and prefer attractive faces, according to Langlois et al. 1990. 8 The paper included two studies. In the first study, I quote “infants interacted with a stranger in the presence of their mother. Attractiveness of the stranger was manipulated by having thin, lifelike, latex theatre masks constructed by a professional mask maker to be either attractive or unattractive.” 89 babies were recruited for the study, all 12-month-old, but 29 were removed from the study. The study believed this was the earliest mark at which social behaviour could be observed.

In Study 2, infants played with attractive and unattractive dolls whose faces were constructed by tracing facial features from photographs of infants who had been rated by adults as more and less attractive”.

The charm of attractiveness knows no boundaries and can even influence parents. In Langlois et al., 1995, the interactions of babies and their mothers were observed, both as newborns and as 3-month-old babies. 9 The attractiveness of a baby significantly affected how the mother would interact with them. The sample was mostly from low-income families, but all families spoke English and had no known history of alcohol or drug abuse. The sample was also multi-cultural, with a third of mothers being white American, African American, and Mexican American, respectively. The babies were in good health and did not have significant birth complications. Pictures of the babies at both timepoints were taken and rated by undergraduate students for attractiveness.

The study found that mothers of attractive newborns engaged in more affectionate interactions, like kissing or holding the baby close. They were also less attentive to others and focused more attention on their infants. Mothers of unattractive infants were more likely to engage in routine caregiving and were more likely to believe that their infants needed more stimulation. The study also ensured that other variables did not play a part. The mother’s attractiveness was also measured, as was Paternal presence/absence, but the variables showed no main effects on the study. As a side note, the results of this study did not imply that the mothers of unattractive babies were mistreating them, it just found a difference in attitudes.

Attractiveness also starts affecting our social life as soon as it begins. 7 Dion and Berscheid (1972) took pictures of kids in a nursery. A nursery was chosen because “this the stage at which both the self-concept and peer-group relationships are developing.” The photographs are mounted on a large board and children are asked to point who they like and dislike, and “to indicate also those who typically exhibit certain social behaviors, such as ‘fighting a lot.’”. Adult judges rated the children’s pictures for attractiveness. Unattractive boys were liked reliably less by peers, who attributed them more frequently with aggressive and anti-social behaviour. Attractive children tend to be seen as more independent and “not afraid of anything”. Very young unattractive girls proved more popular than attractive girls. Berscheid et al. 1974 explains that popularity for less attractive girls reduces as age progress, while attractive girls’ popularity increases. The paper also believes that cultural norms may influence attractive girls’ increasing popularity with age.

Dion (1972) also found that unattractive kids tend to be perceived as having more of an anti-social nature by adults too. 7 Transgressions allegedly committed by a seven-year-olds, from a teacher’s daily journal reports, were shown to a group of female college student subjects. Transgressions could be either minor or severe, and were presented with the student’s name, age and photograph. For minor transgressions attractiveness had no effect on the subject’s perception, but for severe transgressions less attractive kids were rated as having more chronic anti-social problems. Harari and McDavid (1969) also found that unpopular children tend to be “snitched on” or “finked” by peers more often.

Effects on our Dating Life

Walster, Aronson, Abrahams, and Rottmann (1966) tested a hypothesis called Matching, which they derived from Level of Aspiration Theory. 7 I quote: “They reasoned that one’s romantic aspirations are influenced by the same factors that influence one’s level of aspiration in other areas-the desirability of the goal and the perceived probability of attaining it”. A person’s own perceived social desirability will guide the level of social desirability in their mates. Although everyone tends to prefer socially desirable people, if you do not believe you have a chance of successfully obtaining their attention, you will aim for less socially desirable people. The theory was tested in two separate experiments, the first one by the previously mentioned source and the second one by Berscheid et al. (no date stated).

In the first experiment students were paired on blind dates for a dance. The pairs were completely random, except for heights, as the research made sure that the men were taller than their paired woman. They rated attractiveness of participants, and then questionnaires were provided during the intermission of the dance. These questionnaires included questions that helped determine how much they wanted to see their partner again. The study found a 0.89 correlation between perceived physical attractiveness and a desire to see the partner again. The second experiment was similar, except for the fact that men could choose their partners. Everyone preferred physically attractive partners, but less attractive people (as rated by judges) tend to choose less attractive dates than highly attractive individuals. Sugiyama (2015) posits that because mating competition can be costly, it is to one’s advantage to assess the potential rivals before competing with them. “Ancestral males capable of doing this could save time and energy by forgoing, avoiding, or subverting competition with those rivals they were unlikely to outcompete”. 3 Why aim for the stars, when you know you will not make it? Or, why aim for the clouds when you can make it to the stars?

The attractiveness of an individual’s partner also plays a part on how the individual is perceived by peers. Sigall and Landy had a man paired with either an attractive or non-attractive woman. The two were presented to a group of subjects. To one half they presented as romantically involved and to the other half they stated that they had no connection, neither romantic nor any other type. They were then asked to state the “overall impression of the man, to indicate how well they thought they would personally like him, and to rate him on a number of personality scales”. When the man had an attractive “girlfriend”, he had more favourable impressions, and when they had an unattractive “girlfriend” he was viewed more negatively. When there was no connection between the two, there seemed to be no influence by the woman on his impressions to the subjects.

Shorter statures can impact attractiveness ratings of both sexes, but are much more significant on men because women tend to prefer dating men taller than themselves. 73 Modern populations tend to create positive associations between male stature and health. Quoting Sugiyama: “Tall, strong, athletic men are strongly desired as marriage partners (Buss & Schmitt, 1993), and taller than-average men are preferred to men of short or average stature as dates and mating partners (Ellis, 1992). In analyses of personal ads, 80% of women who stated height preferences wanted men 6 feet tall or taller (Cameron, Oskamp, & Sparks, 1977). Ads placed by taller men receive more responses (Lynn & Shurgot, 1984; Pawlowski & Koziel, 2002). Women even seem to take height into consideration in sperm donors (Scheib, Kristiansen, & Wara, 1997).”3 Height in men does not only affect dating life, but can also affect employment opportunities and even Presidential Elections (US). Although it seems like men do not take women’s height into account as much, there seem to be upsides and downsides. As an upside, offspring of taller women exhibit lower child mortality. A downside (or upside, depending on a women’s height) is that “women of mean height had the highest number of marriages or long-term mates and were least likely never to have had a long-term mating relationship.”3

Berscheid et al. (1974) remind us that physical attraction is not always a permanent trait. Puberty can transform a child’s physical attractiveness, for better or for worse, and older age can have similar effects. Schonfeld (1969) “noted that, especially with boys, the late maturing is more likely than their early-maturing peers to encounter a generally unfavourable socio-psychological environment resulting in an adverse effect on their personality adaptations”.7

Weight can provide significant cues into an individual’s health and genetics, but in the context of attraction it differs between cultures. 3 For women, specifically, fat stores support fertility, pregnancy and lactation. Preferred female body fat levels increase with the likelihood of food shortages. Quoting Sugiyama: “Among 12 line drawing stimulus figures ranging from anorexic to obese, British, Kenyan, and Ugandan subjects rated normal weight figures most attractive (Furnham & Radley, 1989), but Kenyans and Ugandans rated high-weight figures significantly more attractive than did British subjects or Kenyans living in Britain (Furnham & Alibhai, 1983; Furnham & Baguma, 1994)”. However, even the fattest woman from cultures that have higher risk of food shortages have less subcutaneous fat than the average U.S. female college student. These cultures have not yet linked obesity with health issues, such as impaired mobility or susceptibility to illness. 3

Fitness cues for men play by different rules. Again, quoting Sugiyama: “Faurie et al. (2004) found that male and female college students who participated in competitive sports or were enrolled in sports curricula reported higher numbers of opposite-sex sex partners than those who were not involved with sports. High-level competitors reported more previous-year opposite-sex partners than lower level competitors. For males but not females, BMI was positively associated with reported previous-year mates, although it could not be analytically separated from the sports participation variable. Manning and Taylor (2001) found evidence that level of sports performance is positively associated with testosterone markers.”3 Men also tend to feel more sexual jealousy from fitter, taller and more muscular men.

Effects on Expectations

Attractive people are attributed many more positive qualities, and people tend to have higher expectations of them. Dion, Berscheid, and Walster (1972) showed subjects of both genders three photos of people and were asked to rate them along several dimensions. Half of the subjects received pictures of women, while the other half received pictures of them. The people that were photographed varied in physical attractiveness. Dion et al. found that: “Attractive people of both sexes were expected to be more likely to possess every personality trait which had been determined to be ‘socially desirable’ in a preliminary study. Physically attractive people, for example, were perceived to be more likely to be sexually warm and responsive, sensitive, kind, interesting, strong, poised, modest, sociable, and outgoing than persons of lesser physical attractiveness. They were also seen more likely to be ‘exciting dates,’ to be ‘nurturant’ individuals, and to have ‘better character’ than persons of lesser attractiveness”. Subjects were also asked to predict the fate of the people in the photographs. More physically attractive people would be predicted to have more prestigious occupations, be better husbands or wives, and have happier marriages than less attractive people.7

Clifford and Walster (1973) asked 5th grade schoolteachers to examine a student’s report card and to give an estimate on “[..] the student’s I.Q., his parent’s attitudes toward school, the pupil’s social status with his peers, and their estimate of the student’s future educational accomplishments”.7 The teachers represented one of 400 schools in the state of Missouri (US). The teachers were provided with the student’s grades, which contained areas such as “reading, language, arithmetic, social studies, science, art, music and physical education”, plus three personal trait areas: “healthful living, personal development and work habits and attitudes”. A list of itemized absences during the school year, and a picture of the student was also provided. The picture could be one of six attractive boys or girls, or six unattractive boys or girls. As predicted, attractive children had higher estimates of I.Q., were expected to attain higher education levels, and was assumed to have more interested parents, in comparison to less attractive students. The gender of the student or the teacher did not affect the results meaningfully.

This effect is also seen in later life. Landy and Sigall (no date given) provided male college students with an essay allegedly written by another female student. The female student could be either attractive or unattractive. Some subjects evaluated the essay without knowledge of the author’s attractiveness. They discovered that “he writer’s ability and her work were evaluated most favourably when she was attractive, intermediately when her appearance was unknown, and least favourably when she was unattractive. They also found that the impact of the writer’s attractiveness was most pronounced when the quality of her work was objectively poor”.

Final Remarks

As we have discovered, attraction works at multiple dimensions, is easily biased and depends on a lot of context. Attempting to classify personal facial patterns of attraction will prove simpler than attempting to find patterns of attraction accross all traits. It complety removes the variable of personality cues and removes some physical cues. Height, for example, is completely removed as a variable. But weight or age can still be estimated from the picture of a face. The next step is to begin gathering data, and then train a model to categorize the images. The second part of this series of blog posts on Facial Attractiveness, a link will be added here once it’s published.

References and Notes

  1. Cronin, H. (1991). The Ant and the Peacock: Altruism and Sexual Selection from Darwin to Today. Cambridge University Press. Google Books. ↩

  2. Thornhill, R., & Gangestad, S. W. (1994). Human fluctuating asymmetry and sexual behavior. Psychological Science, 5(5), 297-302. DOI. ↩ ↩2

  3. Sugiyama, L. S. (2015). Physical attractiveness in adaptationist perspective. In D. M. Buss (Ed.), The handbook of evolutionary psychology (pp. 221-242). Wiley. DOI. ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13

  4. Confer, J. C., Perilloux, C., & Buss, D. M. (2010). More than just a pretty face: Men’s priority shifts toward bodily attractiveness in short-term versus long-term mating contexts. Evolution and Human Behavior, 31(5), 334-341. DOI. ↩

  5. Buss, D. M., & Schmitt, D. P. (1993). Sexual strategies theory: An evolutionary perspective on human mating. Psychological Review, 100(2), 204-232. DOI. ↩ ↩2 ↩3

  6. Buss, D. M. (1989). Sex differences in human mate preferences: Evolutionary hypotheses tested in 37 cultures. Behavioral and Brain Sciences, 12(1), 1-14. DOI. ↩ ↩2 ↩3 ↩4

  7. Berscheid, E., Walster, E., & Berkowitz, L. (1974). Physical attractiveness. In Advances in Experimental Social Psychology (Vol. 7, pp. 157-215). Academic Press. DOI. ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8

  8. Langlois, J. H., Roggman, L. A., & Rieser-Danner, L. A. (1990). Infants’ differential social responses to attractive and unattractive faces. Developmental Psychology, 26(1), 153-159. DOI. ↩

  9. Langlois, J. H., Ritter, J. M., Casey, R. J., & Sawin, D. B. (1995). Infant attractiveness predicts maternal behaviors and attitudes. Developmental Psychology, 31(3), 464-472. DOI. ↩